Electric Charges and Fields — Physics STD 12 Science — Question

An electric dipole is placed at the centre of a sphere, choose the correct options:

The slits in a Young's double slit experiment have equal width and the source is placed symmetrically with respect to the slits. The intensity at the central fringe is I₀. If one of the slits is closed, the intensity at this point will be:

The logic behind ‘NOR’ gate is that it gives

(a) High output when both the inputs are low

(b) Low output when both the inputs are low

(c) High output when both the inputs are high

(d) None of these

A wire of length L and 3 identical cells of negligible internal resistances are connected in series.  Due to current, the temperature of the wire is raised by ∆ T in a time t.  A number N of similar cells is now connected in series with a wire of the same material and cross – section but of length 2 L.  The temperature of the wire is raised by the same amount ∆ T in the same time t.  the value of N is

(a) 4

(b) 6

(c) 8

(d) 9

A strip of copper and another of germanium are cooled from room temperature to 80K. The resistance of:

Same current i = 2A is flowing in a wire frame as shown in figure. The frame is a combination of two equilateral triangles ACD and CDE of side 1m. It is placed in uniform magnetic field B = 4T acting perpendicular to the plane of frame. The magnitude of magnetic force acting on the frame is

(a) 24 N

(b) Zero

(c) 16 N

(d)  8 N

A piece of fuse wire melts when a current of 15 ampere flows through it. With this current, if it dissipates 22.5 W, the resistance of fuse wire will be

(a) Zero

(b) 10 Ω

(c) 1 Ω

(d) 0.10 Ω

An  AM radio wave is emitted by a radio antenna and travels across flat ground. Find out the direction of the magnetic field component of the wave?

The curve between the activity A of a radioactive sample and the number of active atoms N is

(a)

(b)

(c)

(d)